Index: sys/kern/subr_stack.c
===================================================================
--- sys/kern/subr_stack.c
+++ sys/kern/subr_stack.c
@@ -182,9 +182,13 @@
 		    &offset, flags);
 		if (error == EWOULDBLOCK)
 			return (error);
-		sbuf_printf(sb, "#%d %p at %s+%#lx\n", i, (void *)st->pcs[i],
-		    namebuf, offset);
+		if (tty_info_kstacks == 1)
+			sbuf_printf(sb, "#%d %p at %s+%#lx\n", i,
+		    (void *)st->pcs[i], namebuf, offset);
+		else if (tty_info_kstacks == 2)
+			sbuf_printf(sb, "%s+%#lx ", namebuf, offset);
 	}
+	sbuf_nl_terminate(sb);
 	return (0);
 }
 
Index: sys/kern/tty_info.c
===================================================================
--- sys/kern/tty_info.c
+++ sys/kern/tty_info.c
@@ -239,9 +239,33 @@
 }
 
 #ifdef STACK
-static bool tty_info_kstacks = true;
-SYSCTL_BOOL(_kern, OID_AUTO, tty_info_kstacks, CTLFLAG_RWTUN,
-    &tty_info_kstacks, 0,
+int tty_info_kstacks = 1;
+
+static int
+sysctl_tty_info_kstacks(SYSCTL_HANDLER_ARGS)
+{
+	int error, val;
+
+	val = tty_info_kstacks;
+	error = sysctl_handle_int(oidp, &val, 0, req);
+	if (error != 0 || req->newptr == NULL)
+		return (error);
+
+	switch (val) {
+	case 0:
+	case 1:
+	case 2:
+		tty_info_kstacks = val;
+		break;
+	default:
+		error = EINVAL;
+	}
+
+	return (error);
+}
+SYSCTL_PROC(_kern, OID_AUTO, tty_info_kstacks,
+    CTLFLAG_RWTUN | CTLFLAG_MPSAFE | CTLTYPE_INT, NULL, 0,
+    sysctl_tty_info_kstacks, "I",
     "Enable printing kernel stack(9) traces on ^T (tty info)");
 #endif
 
@@ -337,7 +361,7 @@
 		state = "unknown";
 	pctcpu = (sched_pctcpu(td) * 10000 + FSCALE / 2) >> FSHIFT;
 #ifdef STACK
-	if (tty_info_kstacks) {
+	if (tty_info_kstacks > 0) {
 		if (TD_IS_SWAPPED(td))
 			sterr = ENOENT;
 		else
@@ -366,7 +390,7 @@
 	    pctcpu / 100, rss);
 
 #ifdef STACK
-	if (tty_info_kstacks && sterr == 0)
+	if (tty_info_kstacks > 0 && sterr == 0)
 		stack_sbuf_print_flags(&sb, &stack, M_NOWAIT);
 #endif
 
Index: sys/sys/stack.h
===================================================================
--- sys/sys/stack.h
+++ sys/sys/stack.h
@@ -31,6 +31,8 @@
 #ifndef _SYS_STACK_H_
 #define	_SYS_STACK_H_
 
+#ifdef	_KERNEL
+
 #include <sys/_stack.h>
 
 #ifdef _SYS_MALLOC_H_
@@ -39,6 +41,8 @@
 
 struct sbuf;
 
+extern int tty_info_kstacks;
+
 /* MI Routines. */
 struct stack	*stack_create(int);
 void		 stack_destroy(struct stack *);
@@ -69,4 +73,6 @@
 void		 stack_save(struct stack *);
 int		 stack_save_td(struct stack *, struct thread *);
 
+#endif	/* _KERNEL */
+
 #endif